A large number of documents, such as passports and airline tickets, now encode data in the form of a barcode. Further security features are often added to such documents in order to increase the security, such as watermarks, the owner's photograph and written details of the document's rightful owner.
Highly skilled forgers can produce documents that look exceptionally similar to genuine documents and which cannot be readily detected by security personnel who have only a limited amount of time in order to verify the authenticity of the information presented to them in a document.